code: def testInitialGeneration(self):
      rlt = rl_tuner.RLTuner(
          self.output_dir, note_rnn_checkpoint_dir=self.checkpoint_dir
      )
  
      plot_name = "test_initial_plot.png"
      rlt.generate_music_sequence(
          visualize_probs=True, prob_image_name=plot_name
      )
      output_path = os.path.join(self.output_dir, plot_name)
      self.assertTrue(os.path.exists(output_path))
  
file_path: magenta/magenta/models/rl_tuner/rl_tuner_test.py
imports: import os
  import os.path
  import tempfile
  from magenta.models.rl_tuner import note_rnn_loader
  from magenta.models.rl_tuner import rl_tuner
  import matplotlib
  import matplotlib.pyplot
  import tensorflow.compat.v1
label_desc: Use image node_id 4 for calling the RLTunerTest obj's underlying member method code with example usage: obj.testInitialGeneration() without return types